/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.messaging.support;

import org.springframework.lang.Nullable;
import org.springframework.messaging.MessageHeaders;
import org.springframework.util.IdGenerator;

/**
 * A {@link org.springframework.messaging.support.MessageHeaderInitializer MessageHeaderInitializer}
 * to customize the strategy for ID and TIMESTAMP message header generation.
 *
 * @author Rossen Stoyanchev
 * @since 4.1
 */
public class IdTimestampMessageHeaderInitializer implements MessageHeaderInitializer {

    private static final IdGenerator ID_VALUE_NONE_GENERATOR = () -> MessageHeaders.ID_VALUE_NONE;


    @Nullable
    private IdGenerator idGenerator;

    private boolean enableTimestamp;


    /**
     * Configure the IdGenerator strategy to initialize {@code MessageHeaderAccessor}
     * instances with.
     * <p>By default this property is set to {@code null} in which case the default
     * IdGenerator of {@link org.springframework.messaging.MessageHeaders} is used.
     * <p>To have no ids generated at all, see {@link #setDisableIdGeneration()}.
     */
    public void setIdGenerator(@Nullable IdGenerator idGenerator) {
        this.idGenerator = idGenerator;
    }

    /**
     * Return the configured {@code IdGenerator}, if any.
     */
    @Nullable
    public IdGenerator getIdGenerator() {
        return this.idGenerator;
    }

    /**
     * A shortcut for calling {@link #setIdGenerator} with an id generation strategy
     * to disable id generation completely.
     */
    public void setDisableIdGeneration() {
        this.idGenerator = ID_VALUE_NONE_GENERATOR;
    }

    /**
     * Whether to enable the automatic addition of the
     * {@link org.springframework.messaging.MessageHeaders#TIMESTAMP} header on
     * {@code MessageHeaderAccessor} instances being initialized.
     * <p>By default this property is set to false.
     */
    public void setEnableTimestamp(boolean enableTimestamp) {
        this.enableTimestamp = enableTimestamp;
    }

    /**
     * Return whether the timestamp header is enabled or not.
     */
    public boolean isEnableTimestamp() {
        return this.enableTimestamp;
    }


    @Override
    public void initHeaders(MessageHeaderAccessor headerAccessor) {
        IdGenerator idGenerator = getIdGenerator();
        if (idGenerator != null) {
            headerAccessor.setIdGenerator(idGenerator);
        }
        headerAccessor.setEnableTimestamp(isEnableTimestamp());
    }

}
